Cutting by use of rotating axially moving tool – With means to regulate operation by use of templet – tape,...
Patent
1996-07-16
1998-05-26
Bishop, Steven C.
Cutting by use of rotating axially moving tool
With means to regulate operation by use of templet, tape,...
408 10, 408 8, 408 16, 408 56, 408 57, 408137, B23B 3908, B23Q 1512, B23Q 1524, B23Q 1110
Patent
active
057555370
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates generally to the field of portable drills and more particularly to a portable drill for fastening onto the drilling location of large workpieces for precision drilling work by means of a tool through which a liquid lubricant is conducted to the tool cutting edges, having a tool spindle which is displaceable in its axial direction by a separate drive with a tool holder, through which the lubricant is fed and a drive for the rotating axial advance of the tool spindle.
Such a drill is used in all precision drilling work in which the workpieces are of such a size that they cannot be drilled on stationary drilling machines. A preferred field of use of such drills is in the aeronautical industry in order, for instance, to produce, in airplane construction, those holes which are to be provided for the attachment between the fuselage and the wings. The drill in question is either arranged fixed on an auxiliary device or, in variable use, is employed in locking bushings, in templates, or in similar holding devices. Particularly exact precision of machining on the part of such drills is required upon the reaming of previously produced holes, for which purpose conical reaming tools having a conical shoulder are used.
THE PRIOR ART
The prior art related to drills including the drill shown in U.S. Pat. No. 4,688,970. U.S. Pat. No. 4,688,970 shows a drill which has a drive motor which assures the feeding of the work spindle towards the workpiece and back from it. Sensors are seated on the tool spindle in order to check that the drill complies with the working data determined over the working path, and in particular reaches the predetermined depth of drilling with the tool in order then to be withdrawn again from the borehole. Auxiliary means for detecting the top side of the workpiece in order to be able to determine the depth of penetration of the tool into the workpiece from that point are not present in the known apparatus. This is true also of other previously known drills which have only a single drive, both for the rotating of the tool spindle and for the feeding thereof. In these machines, when they are under load, the feed decreases also simultaneously with the speed of rotation; on the other hand, the basic speed of rotation upon idle travel must not be selected too high, so that the idle distances here can be moved over only with relatively low speed.
One essential disadvantage of the known drill machine lies in its high consumption of lubricant, this being a drilling liquid of high quality which is very expensive. The amount of lubricant fed is established empirically based on an estimate of the drilling or reaming process, regardless of the length of engagement of the tool. The drilling or reaming tools used for precision holes have, distributed over their entire cutting length, radial holes which are supplied from a central feed channel. Since the cutting agent is fed continuously in the known embodiments, overdosing takes place as long as the tool is not in engagement over its entire cutting length. Also upon the pulling back of the tool without drilling or reaming work, the lubricant continues to be fed, unutilized, in the known drills. As a whole, therefore, the consumption of lubricant is about ten times as high as required from a purely theoretical standpoint for the actual cutting process.
The known drills also have disadvantages structurally. The tool spindle is mounted at the rear of the machine in an axial conveying thread which is necessary for the feed. Despite additional supporting of the spindle in the front region of the machine, movements of radial deflection are unavoidable, which impairs the accuracy of the drilling. Furthermore, the machining distance, the drilling depth, cannot be precisely determined in the known machines since for this, a depth stop is required which is placed on the wall of the material surrounding the hole in question and which indicates that the drilling depth has been reached in the manner that the tool s
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patent: 4514123 (1985-04-01), Johnstone et al.
patent: 4688970 (1987-08-01), Eckman
patent: 5123789 (1992-06-01), Ohtani et al.
patent: 5613810 (1997-03-01), Bureller
Baxley Esq. Charles E.
Bishop Steven C.
Johannes Lubbering AG
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